HESI A2 Chemistry Test
25 Questions
Step-by-step Answer Explanations
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LATEST UPDATE
, 1. 1. Question
Which of the following represents the basic unit of mass in the metric system?
Liter
Meter
Kelvin
Gram
Answer: Gram
The metric system has basic units for different types of measurements:
Liter is incorrect because that is the metric unit that measures volume.
Meter is incorrect because that is the metric unit that measures length.
Kelvin is incorrect because that is the metric unit that measures temperature.
2. 2. Question
Which of the following is an example of a decomposition reaction?
2H2O(l)→2H2(g)+O2(g)
CH4(g)+2O2(g)→CO2g+2H2O(l)+energy
, Na(s)+Cl2(g)→2NaCl(s)
AgNo3(aq)+NaCl(s)→AgCl(s)+NaNO3(aq)
Answer: 2H2O(l)→2H2(g)+O2(g)
A decomposition reaction occurs when a single compound breaks down into two or more
simpler substances. In this reaction, water decomposes into hydrogen gas and oxygen gas.
Na(s)+Cl2(g)→2NaCl(s)
It is incorrect because this is an example of a synthesis reaction. In a synthesis reaction, two or
more simple substances combine to form a more complex product. In this case,
sodium (Na) reacts with chlorine gas (Cl2) to form sodium chloride (NaCl). This is the opposite
of decomposition because instead of breaking down, elements are combining to form a
compound.
CH4(g)+2O2(g)→CO2g+2H2O(l)+energy
It is incorrect because this is an example of a combustion reaction. A combustion
reaction typically involves a hydrocarbon (like methane (CH4) (reacting with oxygen to produce
carbon dioxide, water and energy (usually in the form of heat or light). Combustion reactions
are exothermic, meaning they release energy.
AgNo3(aq)+NaCl(s)→AgCl(s)+NaNO3(aq)
It is incorrect because this is an example of a double replacement reaction. A double
replacement reaction occurs when two compounds exchange components to form two new
compounds. Here, silver nitrate (AgNO3) and sodium chloride (NaCl) react, exchanging ions to
form silver chloride (AgCl) and sodium nitrate (NaNO3). This is not a synthesis or decomposition
reaction because two compounds are reacting, not breaking down or combining.
3. 3. Question
What is the solvent in an aqueous solution?
Salt
Oxygen
Water
25 Questions
Step-by-step Answer Explanations
Pass Guarantee
LATEST UPDATE
, 1. 1. Question
Which of the following represents the basic unit of mass in the metric system?
Liter
Meter
Kelvin
Gram
Answer: Gram
The metric system has basic units for different types of measurements:
Liter is incorrect because that is the metric unit that measures volume.
Meter is incorrect because that is the metric unit that measures length.
Kelvin is incorrect because that is the metric unit that measures temperature.
2. 2. Question
Which of the following is an example of a decomposition reaction?
2H2O(l)→2H2(g)+O2(g)
CH4(g)+2O2(g)→CO2g+2H2O(l)+energy
, Na(s)+Cl2(g)→2NaCl(s)
AgNo3(aq)+NaCl(s)→AgCl(s)+NaNO3(aq)
Answer: 2H2O(l)→2H2(g)+O2(g)
A decomposition reaction occurs when a single compound breaks down into two or more
simpler substances. In this reaction, water decomposes into hydrogen gas and oxygen gas.
Na(s)+Cl2(g)→2NaCl(s)
It is incorrect because this is an example of a synthesis reaction. In a synthesis reaction, two or
more simple substances combine to form a more complex product. In this case,
sodium (Na) reacts with chlorine gas (Cl2) to form sodium chloride (NaCl). This is the opposite
of decomposition because instead of breaking down, elements are combining to form a
compound.
CH4(g)+2O2(g)→CO2g+2H2O(l)+energy
It is incorrect because this is an example of a combustion reaction. A combustion
reaction typically involves a hydrocarbon (like methane (CH4) (reacting with oxygen to produce
carbon dioxide, water and energy (usually in the form of heat or light). Combustion reactions
are exothermic, meaning they release energy.
AgNo3(aq)+NaCl(s)→AgCl(s)+NaNO3(aq)
It is incorrect because this is an example of a double replacement reaction. A double
replacement reaction occurs when two compounds exchange components to form two new
compounds. Here, silver nitrate (AgNO3) and sodium chloride (NaCl) react, exchanging ions to
form silver chloride (AgCl) and sodium nitrate (NaNO3). This is not a synthesis or decomposition
reaction because two compounds are reacting, not breaking down or combining.
3. 3. Question
What is the solvent in an aqueous solution?
Salt
Oxygen
Water
